RE: NI-6111 and Comedi

Thanks Rolf for your input.

Dave,
It's unfortunate that Comedi does not work very well with the 6111.  Comedi
is a great package, but for, the moment, I think it would be a good idea to
remove the 6111 from the list of devices that Comedi supports.  We just
spent a few thousand dollars buying the 6111 and peripheral equipment, based
on the fact that Comedi claims to support it.  It is painful to find out now
that the 6111 really doesn't work under Comedi.

I'll keep playing with it for a little while longer.  If I figure out
anything new, I'll post to the mailing list.

Thanks again,
Juan Gonzalez


-----Original Message-----
From: Rolf Mueller [mailto:rolf.mueller_at_uni-tuebingen.de]
Sent: Tuesday, July 16, 2002 3:14 AM
To: Juan Gonzalez
Cc: comedi_at_comedi.org
Subject: Re: NI-6111 and Comedi


Dear Juan,

welcome to the club of frustrated NI-611x board users.

On Mon, Jul 15, 2002 at 07:11:25PM -0400, Juan Gonzalez wrote:

> I've been trying to use the NI-6111 DAQ with the Comedi driver, but with
> only limited success.  My goal is simply to drive an analog output signal
> and to read an analog input signal.  There seems to be some problems,
> especially on the input side.  I've read some of the recent archives on
this
> topic, but I'm not clear as to whether the code now works correctly for
this
> device or not.

It does not.

> However, there are problems on the analog input side.  The command "./inp"
> does not seem to work.  I get errors like "ni_E: timeout 1" and "ni_E:
> timeout 2".  Has anyone else seen this?

Yes, sure, all the time.

> I looked into the driver code and started experimenting with it.  The
> timeout occurs in the function ni_ai_insn_read (in ni_mio_common.c).  It
> appears that after the strobe to AI_CONVERT_Pulse, the ADC FIFO remains
> empty, no matter how long we wait.

... or at least the AILWEF flag (bit 7) in the 611x Status register
(Offset 1) seems to indicate that the FIFO remains empty. I don't know
where the error is.

>  Increasing the timeout value doesn't seem to improve things.
>  However, if I strobe the AI_CONVERT_Pulse a second time, then I get
>  some data in the FIFO (!?).

I assume you are doubling the command
"win_out(1,AI_Command_1_Register);"? - This works for me in
ni_ai_insn_read() (no "timeout 2" message, i.e., AILWEF has been set
here apparently) but not in ni_load_channelgain_list() (timeout 1)
called from ni_ai_insn_read() and ni_ai_cmd().

> I'm not sure exactly what is happening here since National
> Instruments has not published the register level description for the
> 6111.

Even with this description, it is not clear why this happens.

> Does Comedi handle analog input for this device?

No. It is broken, I am afraid. My guess is that there is a special
little magic that needs to be done with these boards, that is not done
by comedi.

Best wishes,
Rolf


--
Rolf Mueller, rolf.mueller_at_uni-tuebingen.de
Biosonar Lab, Tuebingen University,
Morgenstelle 28, 72076 Tuebingen
Phone +49 7071 29-74838  Fax. +49 7071 292618

Received on 2002-07-16Z14:23:08